Limit stop mechanism



July 1965 R. E. STAUFFER LIMIT STOP MECHANISM Filed March 6, 1962 FIG.2

3 INVENTOR,

ROSS E. STAUFFER BY i A! Z ATTORNEY.

United States Patent O 3,192,780 LIMIT STOI MECHANISM Ross E. Staufier, Wall Township, Monmouth County, NJ. (Box 225, RR. 2, Farmingtlale, NJ.) Filed Mar. 6, 1962, Ser. No. 177,929 3 Claims. (Cl. 74-'10.2) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

The present invention relates to a limit stop particularly adapted for controlling and limiting the number of rotational turns of a shaft.

In the utilization and operation of many mechanical and electronic equipments there is often a need for the inclusion within such devices, of a means for accurately controlling the clockwise or counterclockwise rotation of a shaft through a prescribed and limited number of turns.

The present invention has as its primary object the pro vision of a limit stop mechanism to control the number of rotational turns of a shaft which is wholly confined within, and is integral with, a knob which controls the movement of the shaft.

An important feature of the invention lies in the simplicity of the construction of the limit stop mechanism in that only one moving part is all that is necessary for its operation.

Another feature of the invention resides in the further provision of means for varying or limiting the whole or fractional number of turns of a shaft as such need arises.

Another feature of the invention resides in the provision of a novel knob, used in conjunction with said limit stop mechanism, that allows for adjustment to likewise control the number of turns, either fractional or whole, of a shaft controlled by said knob.

The invention can best be understood from the following description to be read in view of the accompanying drawing in which:

FIGURE 1 is an exploded view showing the various component parts of the limit stop mechanism and a shaft to which it is applied;

FIGURE 2 is a cross sectional view, taken on the line 2-2, of a knob, including the limit stop mechanism, and its associated shaft; and

FIGURE 3 is a view in perspective showing another form of knob including an adjustment means to control the number of turns of a shaft to which said knob is affixed.

Referring to the drawing, and particularly to FIGURE 2, there is shown a chassis 111 which serves as a support means for a mechanism 13 which in turn is controlled by a shaft 15, the rotational movement of which is to be controlled over a predetermined number of revolutions. The shaft 15 is mounted and supported in a panel 17 which is affixed to the chassis 11. The panel 17 has an opening 19, provided with a pair of diametrically opposed keyways 21. The opening 19 serves as a support means for the shaft 15. As can be seen in FIGURE 1, the shaft 15 includes a reduced diameter portion 15a which serves to support a collar 23. The reduced portion 15a of the shaft is free to rotate within the bore of the collar. The collar 23 is externally threaded throughout its exterior surface and further provided with a flange-like terminus 25 at one end thereof. The terminal is provided with a pair of diametrically opposing keys 27 which are adapted to engage and mesh with the keyways 21 of the panel 17. Such engagement between the panel 17 and the collar 23 serves as a means for supporting the knob arrangement, herein- 3,192,780 Patented July 6, 1965 ice after described, and in addition secures the collar 23 from any rotational movement. Threadably engageable on the collar 23 is an internally threaded traveling slug 29 which is provided with a pair of diametrically opposed keys 31 on its peripheral surface. The slug 29 is keyed within the bore of a knob 33 which is provided with a pair of opposing keyways 35 adapted to accommodate the keys 31 'of the traveling slug 29. In order to secure mutual rotation of the knob 33 and the shaft 15 there are provided set screws 37 whichmake fast the knob and shaft.

The operation of the limit stopmechanis'm, herein described, will be apparent from a study ofFIGURE 2. As the knob 33 and shaft are rotated in one direction the slug 29 will travel along the collar 23 until the slug reaches either the surface of the panel 17 or the inner end surface wall of the knob. When the traveling slug reaches either one of said locations it is obvious that the knob can no longer be rotated thus insuring a fixed number of rotational turns of the shaft.

Included as part of the inventive concept herein are means to variably adjust and limit the rotational movements of the shaft. One such means is shown in phantom outline in FIGURE 1, designated as 29A, and comprises a traveling slug identical to the slug 29 except that slug 29A has an overall length greater than that of slug 29. Obviously such larger slug will have a shorter sweep of travel than that of a smaller sized slug thereby limiting the number of rotational turns of the knob and shaft. It is also contemplated that any number of slugs of varying length can be used interchangeably to secure any desired number of turns of the shaft. All that is required is to remove the knob and insert the appropriate sized traveling slug dependent upon the particular requirement.

In FIGURE 3 there is shown a knob construction that will control and limit the sweep, or length of travel, of the traveling slug 29 thereby controlling the number of turns of the shaft. A knob 39 is provided having an elongated slot 41 on a peripheral surface thereof. Within the slot are shoulders 42 which serve as tracks along which are movable a washer 45 and a screw 43. Confined within the bore of the knob is a movable ring 47 having a threaded opening 49 therethrough. In FIGURE 3 the screw 43 is shown partially threaded through the washer and into and through the opening 49 of the ring 47. At such time the ring 47 can be moved to any location within the bore of the knob. When a desired length of sweep or movement of the slug 29 is needed, the ring is moved to a particular location and the screw 43 is urged into tight fit with the washer 45 thereby firmly securing the washer into engagement against the shoulders 42 and thereby secure the ring 47 in any desired location. It is obvious that the ring 47 will in such instance serve as a stop, in lieu of the inner wall of the knob, to stop further -movement of the traveling slug 29. In such instance only one size slug, such as slug 29, need be used as its limit of travel can be controlled by movement of the ring 47 to any desired location.

What is claimed is:

1. A limit stop mechanism for controlling the number of rotational turns of a shaft comprising an external threaded collar surrounding a portion of said shaft and within which said shaft is rotatable, means for securing the collar from any rotational movement about said shaft, a slug having at least one key on its outer peripheral surface, said slug being threadably engageable on said collar for linear movement on said collar and a knob having a bore and at least one longitudinal keyway that meshes with the key of said slug secured to said shaft whereby said slug is mutually rotatable with said knob in either clockwise or counterclockwise direction, and wherein said knob includes means within said bore for limiting the linear movement of said slug over said collar.

2. A limit stop mechanism for controlling the number of rotational turns of a shaft comprising an externally 5 threaded collar surrounding a portion of said shaft and within which said shaft is rotatable, means for securing the collar from any rotational movement about said shaft, a slug threadably engageable on said collar and having at least one key on its outer peripheral surface, and a knob 10 about said collar secured to said shaft and having at least one internal longitudinal keyway adapted to mesh with the key of said slug for mutual rotation therewith.

3. A mechanism of the kind set forth in claim 1 wherein .said means for limiting thelinear sweep of said slug over said collar comprises a ring slideablymoveable in the bore of the knob to any desired location within said knob and further including means for securely holding the ring in said desired location.

References Cited by the Examiner UNITED STATES PATENTS 9/61 Thompson 74-l0.2 X

FOREIGN PATENTS 344,338 10/20 Germany.

OTHER REFERENCES IBM Technical Disclosure Bulletin, Vol. 4, No. 6, November 1961.

1 DAVID J. WILLIAMOWSKY, Primary Examiner.

THOMAS J. HICKEY, Examiner. 

1. A LIMIT STOP MECHANISM FOR CONTROLLING THE NUMBER OF ROTATIONAL TURNS OF A SHAFT COMPRISING AN EXTERNAL THREADED COLLAR SURROUNDING A PORTION OF SAID SHAFT AND WITHIN WHICH SAID SHAFT IS ROTATABLE, MEANS FOR SECURING THE COLLAR FROM ANY ROTATAIONAL MOVEMENT ABOUT SAID SHAFT, A SLUG HAVING AT LEAST ONE KEY ON ITS OUTER PERIPHERAL SURFACE, SAID SLUG BEING THREADABLY ENGAGEABLE ON SAID COLLAR FOR LINEAR MOVEMENT ON SAID COLLAR AND A KNOB HAVING A BORE AND AT LEAST ONE LONGITUDINAL KEYWAY THAT MESHES WITH THE KEY OF SAID SLUG SECURED TO SAID SHAFT WHEREBY SAID SLUG IS MUTUALLY ROTATABLE WITH SAID KNOB IN EITHER CLOCKWISE OR COUNTERCLOCKWISE DIRECTION, AND WHEREIN SAID KNOB INCLUDES MEANS WITHIN SAID BORE FOR LIMITING THE LINEAR MOVEMENT OF SAID SLUG OVER SAID COLLAR. 